Eric Aaron Dimitris N. Metaxas Franjo Ivancic A Framework for Reasoning about Animation Systems. 47-60 2001 conf/iva/2001 IVA http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2190&spage=0047 db/conf/iva/iva2001.html#AaronMI01